| 摘要 |
PURPOSE:To eliminate the unnecessary outflow of a current and to supply a sufficiently high voltage by interposing the 5th transistor (TR) as a current passage between the control terminal of the 1st TR and the 4th circuit point and outputting the voltage from the 1st circuit point. CONSTITUTION:When a control signal R/W is set to a 0 level, the gate of a TR15 is set to 0V, the source is set to 5V, and the gate potential of the TR15 is held -5V, so this TR15 does not turn on unless the threshold voltage is at >=5V. The threshold voltage of this TR15, however, is -3V, so it does not turn on. Therefore, the high voltage obtained at a circuit point 14 is never discharged through the TR15. Further, when the circuit point 14 is set to a high voltage, the output terminal of a CMOS inverter 25 is held at the 0 level, so the TR21 is still off and the voltage at a circuit point 17 is not discharged through this TR24. Namely, the high voltage is obtained at the circuit point 14 while a signal R/W is at the 0 level. |
